Vibrational Raman and infrared spectroscopic transitions are used to probe the dynamical and structural properties associated with lipid-lipid and lipid-protein interactions in both real and model membrane-bilayer systems. As an example, temperature profiles of multilamellar lipid assemblies composed of either saturated or mixed saturated and unsaturated hydrocarbon chains were compared to profiles for systems containing cholesterol or lanosterol intercalated within the bilayers. Examination of the profiles relevant to interchain interactions and, separately, to intramolecular processes provides detailed information concerning the function and packing characteristics of sterols in membranes. The properties of intrinsic and extrinsic membrane components were examined by Raman spectroscopy. The effects of melitten (a peptide isolated from bee venom) and its fragments on the thermotropic behavior of 1,2-dimyristoyl phosphatidylcholine liposomes were studied as a function of protein concentration. The existence of a distinct boundary lipid, composed of about seven lipid molecules surrounding the peptide, was established for this lipid-protein interface.